Provide a diagram and description of the flow table entries

Provide a diagram and description of the flow table entries that can be
modified in an OpenFlow Switch.

Provide a diagram and description of an SDN Controller and describe
how the SDN Controller works – OpenDaylight is an appropriate
example that you could use.

Solution

Open Flow Switch:

An Open Flow switch is a software program or hardware device that forwards packets in a software-defined networking (SDN) environment. Open Flow switches are either based on the Open Flow protocol or compatible with it.

In a conventional switch, packet forwarding (the data plane) and high-level routing (the control plane) occur on the same device. In software-defined networking, the data plane is decoupled from the control plane. The data plane is still implemented in the switch itself but the control plane is implemented in software and a separate SDN controller makes high-level routing decisions. The switch and controller communicate by means of the Open Flow protocol.

Flow table entries:

The components of flow table entries and the process by which incoming packets are matched against flow table entries.

A flow entry consists of header fields, counters, and actions.

    Header fields

        Counters

      Actions

Each flow table entry contains:

1. Header fields to match against packets.

2. Counters to update for matching packet.

3. Actions to apply to matching packets.

These are flow table entries are used to modified in an open flow switch.

Open Flow is an open standard that enables researchers to run experimental protocols in the campus networks we use every day. Open Flow is added as a feature to commercial Ethernet switches, routers and wireless access points – and provides a standardized hook to allow researchers to run experiments, without requiring vendors to expose the internal workings of their network devices. Open Flow is currently being implemented by major vendors, with Open Flow-enabled switches now commercially available.

SDN controller (software-defined networking controller):

An SDN controller is an application in software-defined networking (SDN) that manages flow control to enable intelligent networking. SDN controllers are based on protocols, such as Open Flow, that allow servers to tell switches where to send packets.

SDN controller is a new paradigm to configure and operate computer networks through a centralized software controller that dictates how the network behaves. The core of this new paradigm is the SDN controller.

There are typically two sets of SDN controllers:

The controller is the core of an SDN network. It lies between network devices at one end and applications at the other end. Any communications between applications and devices have to go through the controller. The controller also uses protocols such as Open Flow to configure network devices and choose the optimal network path for application traffic.

SDN controllers works:

Software Defined Networking, as it evolved from prior proposals, standards, and implementations such as For CES, 4D, and Ethane, is characterized by five fundamental traits: plane separation, a simplified device, centralized control, network automation and virtualization, and openness.

The first fundamental characteristic of SDN is the separation of the forwarding and control planes. Forwarding functionality, including the logic and tables for choosing how to deal with incoming packets based on characteristics such as MAC address, IP address, and VLAN ID, resides in the forwarding plane. The fundamental actions performed by the forwarding plane can be described by the way it dispenses with arriving packets. It may forward, drop, consume, or replicate an incoming packet. For basic forwarding, the device determines the correct output port by performing a lookup in the address table in the hardware ASIC. A packet may be dropped due to buffer overflow conditions or due to specific filtering resulting from a QoS rate-limiting function.

Building on the idea of separation of forwarding and control planes, the next characteristic is the simplification of devices, which are then controlled by a centralized system running management and control software.

Instead of hundreds of thousands of lines of complicated control plane software running on the device and allowing the device to behave autonomously, that software is removed from the device and placed in a centralized controller.

.The controller then provides primitive instructions to the simplified devices when appropriate in order to allow them to make fast decisions about how to deal with incoming packets.

        Three basic abstractions forming the basis for SDN are defined. This asserts that SDN can be derived precisely from the abstractions of distributed state, forwarding, and configuration. They are derived from decomposing into simplifying abstractions the actual complex problem of network control faced by networks today. A historical analogy, note that today’s high-level programming languages represent an evolution from their machine language roots through the intermediate stage of languages such as C.

        SDN is a similar natural evolution for the problem of network control. The distributed state abstraction provides the network programmer with a global network view that shields the programmer from the realities of a network that is actually comprised of many machines, each with its own state, collaborating to solve network-wide problems. The forwarding abstraction allows the programmer to specify the necessary forwarding behaviors without any knowledge of vendor-specific hardware. This implies that whatever language or languages emerge from the abstraction need to represent a sort of lowest common denominator of forwarding capabilities of network hardware.

Working with the network through this configuration abstraction is really network virtualization at its most basic level. This kind of virtualization lies at the heart of how we define Open SDN in this work. The centralized software-based controller in SDN provides an open interface on the controller to allow for automated control of the network. The context of Open SDN, the terms northbound and southbound are often used to distinguish whether the interface is to the applications or to the devices.

A characteristic of Open SDN is that its interfaces should remain standard, well documented, and not proprietary. The APIs that are defined should give software sufficient control to experiment with and control various control plane options. The premise is that keeping open both the northbound and southbound interfaces to the SDN controller will allow for research into new and innovative methods of network operation

Research institutions as well as entrepreneurs can take advantage of this capability in order to easily experiment with and test new ideas. The speed at which network technology is developed and deployed is greatly increased as much larger numbers of individuals and organizations are able to apply themselves to today’s network problems, resulting in better and faster technological advancement in the structure and functioning of networks. The presence of these open interfaces also encourages SDN-related open source projects.

These all are characteristics are used in the SDN (Software Defined Networking) works.

Example of open day light of cloud purpose:

The open day light is appropriate example is Vendors of SDN controllers include Big Switch Networks, HP, IBM, VMWare and Juniper.   A brief look at the Big Switch product, Big Network Controller.   Like Big Switch\'s other SDN products, the controller is based on Open Flow, which enables software to run on numerous types of hardware, rather than being tied down to proprietary equipment from one supplier are used to cloud purpose.